Electric devices comprising a high-voltage winding are used to a large extent in various applications in electricity distribution networks. Examples of non-rotating devices of this kind are transformers and inductors. Traditionally, transformers have included a core of magnetic material around which a high-voltage winding and a low-voltage-winding have been arranged. Traditionally, the magnetic core and its windings have been arranged in a oil-filled container. Such a transformer is relatively big.
High-voltage here means voltages above 1 kV.
In many cases, there is not much space in the places where a transformer is to be located. This is the case, for example, when the transformer is to be located in a built-up area or inside a building. In those cases, it would have been desirable to have a less bulky transformer or a transformer with a geometrical shape that is adapted to the space available. The transformer could then be arranged, for example, in an existing cable trench, along an existing wall or under a roof. In many cases, it is also desirable to provide a transformer with lower weight, for example when the transformer is to be located at the top of a power pole.
When distributing power to dwellings, it is desirable to step down the voltage to normal mains voltage as late as possible in order to minimize the losses. In most cases, the voltage is then stepped down from about 10 kV to 400 V. In many countries, such transformers are usually arranged at the top of a pole. Because of their size, there is a considerable risk that they are blown down, which entails expensive maintenance and repair work. As in the previous example, it is here desirable to minimize the size of the transformer.
Consequently, there is a need for an electric device with smaller dimensions or with different geometrical shape than existing devices to avoid the above problems.